1. Field of the Invention
The invention relates to a thumb support which is incorporated within a glove. More particularly, the invention relates to an anterior or palmar-type thumb support which prevents hyperextension and lateral dislocation of the metacarpophalangeal joint and resultant injury to the ulnar collateral ligament.
2. State of the Art
It is well known that, as a solitary digit, the thumb stands unprotected by immediate adjacent fingers and protrudes from the hand at its metacarpophalangeal (hereinafter "MCP") joint. Hyperextension or lateral dislocation of the MCP joint results in a partial or complete rupture of the ulnar collateral ligament (hereinafter "UCL"). A common mechanism for this type of injury is frequently seen by snow skiers. Snow skiers often sustain an injury to the UCL when their ski pole is fixed and their thumb is suddenly hyperabducted. Also, during a fall, forces are frequently placed on the thumb via the ski pole. The injury so common that it is often called "skier's thumb". Nevertheless, it is not only skier's who are exposed to the risk of this type of thumb injury. Any activity which requires the participant to grasp a pole-like object and/or which risks falling on the hand is subject to producing injury to the UCL. Thus, the injury has also been known as "gamekeeper's thumb" and "breakdancer's thumb". It also often results from "urban cowboy" mechanical bull riding.
The UCL of the thumb MCP joint stabilizes that joint against forces applied in a radial direction to the thumb. When the UCL is damaged, the thumb tends to "run away" from the index finger and the power of pinch is significantly reduced. Treatment of an injury to the UCL often requires complicated microsurgery and it may take eight months to a year before full hand function is recovered. Even in cases of minor injury to the UCL, treatment requires a period of immobilization of the thumb, using a splint, and subsequent physical therapy. It may take twelve to sixteen weeks to recover full use of the thumb.
It is known in the art to provide a glove including a brace to prevent UCL injuries. Primiano et al. U.S. Pat. No. 4,524,464 discloses a safety glove with a modified dorsal thumb spica brace. A pocket within the layers of the glove retains the brace. The brace is a modified dorsal thumb spica beginning distal of the wrist and extending generally to the end of the thumb. The brace extends across the dorsal side of the hand, allowing free movement of the second through fifth digits, and extends on the palmar side distal of the wrist to terminate proximal of the palmar crease. The thumb portion is contoured to resist radial deviation and extension of the thumb, but permit flexion of the MCP and interphalangeal (hereinafter "IP") joints of the thumb towards the fingers.
The dorsal brace is useful in protecting the UCL and MCP joint when a user of the brace attempts to break the force of a fall with an open hand. However, in attempting to provide a brace which does not restrict the use of a ski pole, the dorsal brace allows ski pole pressure to bear directly against the thumb. In addition, the dorsal brace can impinge the metacarpal bone of the thumb, the radial and median nerves, and the surrounding soft tissue of the dorsal aspect of the thumb. With the dorsal brace, the impact and pressure of a ski pole on the thumb is directed to the thumb itself and could fracture or dislocate the IP joint of the thumb.